Republican gubernatorial candidate Rob Astorino on Thursday lambasted a new measure allowing some political candidates to use public funds for their campaigns.

But the only candidate opting into that program is one of Mr. Astorino’s allies: Bob Antonacci, a Republican running to unseat Thomas DiNapoli, a Democrat, as state comptroller.

“That’s up to him if he chooses to do that,” Mr. Astorino, the Westchester County Executive said. “It’s my view that it’s welfare for politicians. It’s using tax dollars taken away from education aid and given to politicians for their robocalls and fancy dinners and awful mail. That’s a priority out of whack.”

GOP members presented a united front at the party’s convention on Wednesday and Thursday in Westchester, where Messrs. Astorino and Antonacci were formally announced as the party’s nominees for their races. But on the matter of public campaign finance, their harmony broke down.

Mr. Antonacci’s praised the program in his remarks at the convention on Wednesday, after he won the GOP’s nomination for comptroller unanimously.

“It is historic,” he said. “Accepting taxpayer dollars to run a statewide campaign is an awesome responsibility…for far too long we’ve seen candidates unable to tell their stories and provide meaningful choice for voters. But not now.”

Public campaign finance is one of the most polarizing issues in Albany on both sides of the aisle.

Supporters say public campaign finance would help even the playing field in politics so candidates who aren’t wealthy or allied with moneyed donors could afford to compete with more affluent candidates.

Its detractors say it is a misallocation of taxpayer money toward political ends, and that most New Yorkers don’t want it.

New York City allows political candidates to partly fund their races with taxpayer dollars.

The measure was championed by Democrats earlier in this legislative session, but many of those Democrats were disappointed when the state budget included a measure that only allowed public funds to be used for the state comptroller’s race and not for any others, such as the governor’s race.

Though long a supporter of public campaign finance, Mr. DiNapoli opted out of the program in protest.

Mr. Antonacci criticized Mr. DiNapoli for that choice, saying on Wednesday that the comptroller was “running from what he asked for.” Mr. DiNapoli has said the program is “a poor excuse for real reforms.”

Mr. Cuomo, a Democrat, has said that the measure is an achievement, because even one statewide election using public funds is more than New York has ever had before. Democratic activists have disagreed.

Mr. Antonacci noted at the convention that it is “frankly ironic” that he will be the only beneficiary of Democratic lobbying for publicly funded statewide campaigns this year, a measure with Republican opposition in Albany.

On Wednesday, Long Island Republican Sen. Dean Skelos was asked about Mr. Antonacci’s choice to use public funds in the race, while his opponent opted out. “I was brilliant for setting up that program,” said Mr. Skelos, who participated in budget negotiations. “Brilliant.”